Source distribution of neuromagnetic slow wave and alpha activity in depressive patients : therapy-dependent changes

Abstract

This study uses magnetoencephalography (MEG) to examine abnormal regional activity in depressed patients and to investigate the change in activity after cognitive-behavioral therapy. The MEG was measured in 24 inpatients meeting the criteria for a ICD-10 (International Statistical Classification of Diseases) diagnosis of mental and behavioral disorders during a resting period prior to psychotherapeutic intervention and at the end of therapy. The patientsâ clinical status was assessed with Beck Depression Inventory (BDI) and Brief Psychiatric Rating Scale (BPRS) at both time points. Before treatment all but four patients received medications. The patient group was compared to 24 healthy subjects, similar in age to the depressive patients. Analysis of symptomatology shows that most depressed patients have moderate depression as measured by BDI scores before treatment. At the end of therapy, the BDI and BPRS scores reveal a decrease in symptomatology relative to the beginning of therapy across all depressed groups. Present findings demonstrate that depressed patients display reduced prefrontal and enhanced parietal activity in delta, theta and alpha frequency bands, compared to controls. After therapy, in addition to symptom improvement, depressed patients show an increase in delta power in the right prefrontal region and a decrease in the right parietal region relative to the beginning of treatment. These results confirm the hypothesis that treatment effects, evaluated by symptom improvement, are accompanied by normalization of delta activity in the prefrontal and parietal regions of right hemisphere in depressed patients.